1. Department of Pharmaceutics and Bioengineering, School of Chemical Engineering, Sichuan University, Chengdu610065, P. R. China
2. Department of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu610041, P. R. China
3. Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu610065, P. R. China